fate: add test for the tile video filter.

tests/lavfi-regression.sh

@@ -58,6 +58,7 @@ do_lavfi "select"             "select=not(eq(mod(n\,2)\,0)+eq(mod(n\,3)\,0))"
 do_lavfi "setdar"             "setdar=16/9"
 do_lavfi "setsar"             "setsar=16/11"
 do_lavfi "thumbnail"          "thumbnail=10"
+do_lavfi "tile"               "tile=3x3"
 do_lavfi "transpose"          "transpose"
 do_lavfi "unsharp"            "unsharp=10:10:-1.5:10:10:-1.5"
 do_lavfi "vflip"              "vflip"

tests/ref/lavfi/tile

+tile                c051503deb65568c6c954b94a895b55d